Fastener for wallboard units



J. G. HAMILTON FASTENER FOR WALL BOARD UNITS May 11, 1943.

3 Sheeis-Sheet 1 Filed July 18, 1959 $5! IIYVEQTOR.

y 1943- J. G. HAMILTON FASTENER FOR WALL BOARD UNITS Filed July 18, 19393 Sheets-Sheet 2 INV NTOR.

y 11, 1943- J. G. HAMILTON 2,319,129

FASTENER FOR WALL BOARD UNITS Filed July 18, 1939 25 Sheets-Sheet 5 i-E3- i? 5%. 1 2' .55. J J 5 is 1]! EN TOR.

Patented May 11, 1943 UNITED STATES PATENT OFFICE FASTENER FOR WALLBOARDUNITS i John G. Hamilton, Orleans County, La.

Application July 18, 1939, Serial No. 285,220

Claims.

This invention is used in relation to wall board, insulating board,composition board and the like substances used in walls of buildings.

The broad objects of the invention are as follows:

1. To provide a concealed fastening means for securing the abutting endsof wall units to each other and to underlying elements to which theseunits are attached.

2. To utilize a suitable gauge wire of proper temper and type in theprocess of manufacture of the concealed clips, instead of the heavier,more expensive, harder to insert, and harder to manufacture sheet-metalclips.

3. The utilization of Celluloid, Bakelite and similar compositionmaterials to be used for the manufacture of clips for wall units.

4. Method for applying wall board at corners and the like with aconcealed fastening means.

5. Method of securing clips to underlying supports so as to take care ofexpansion and contraction of the boards.

More specifically, the invention relates to the provision of wire clipsused singly or in pairs at any given place on the abutting surfaces, orat wall comers, and the like, of two units so that a portion of the clipwill enter the unit from the abutting surface, and offset will lie flushagainst this surface and an extending portion will be adapted to besecured to the underlying support, and/or which can cooperate with anadjacent unit, lying between its back surface and an underlyingsupporting joist or element.

Another object of the invention is the provision of a concealedfastening means for building units of fiber boards whose abutting edgesare tongued and grooved, or the like. One portion of this fasteningmeans penetrates the unit diagonally from the edge surface and may enterthe underlying support -after passing through the back surface of theboard; the other portion of the fastening means preferably passes'justdistil to the edge surface of the unit and enters the underlying supportsecuring the unit at the edge of the unit to the underlying support. Thetongue or groove edge surface of the board next applied is drivenagainst the abutting edge of the end where it has been secured by meansof the fasteners. The second unit applied is held in place at theabutting edges by the tongue and groove interfitting, and is held to thesupporting member as a result of the attachments by the clips in thefirst units abutting edge.

Another object of the invention is the provision of a concealedfastening means for building units which enter the board from what willbe its back surface near its abutting ends, and has a portion extendingout beyond the abutting edge of unit which can be stapled or nailed toan underlying support, or cooperate with an adjacent secured and stapledor nailed unit by having its extending portion between the back of thesecured unit and an underlying support thus securing two abutting unitsin any given place where the clips are used at the abutting ends ofunits. The first abutting edge is secured by a nail being driven intothe underlying support and the second units abutting edge where theextending portion of the clip was shoved between the back surface of theunit and the underlying supporting element or joist of the first securedand nailed board.

Another important object of the invention is the use of wire instead ofsheet-metal members in the process of manufacturing clips to be used oncomposition and other units. This will bring about a very practical andastoundingly marked advance in the utilization of my clips by thebuilding trade.

Heretofore, the manufacture of clips from sheet metal made them so hardto insert that a workmans fingers prohibited the use of them due to thefact that they become torn and blistered after a very short time whenapplying sheet-metal clips. They are also more expensive to make anddistribute due to the initial cost of the sheetmetal as well as thedifference in bulk and the fact that bigger and more expensive machinesare necessary in their manufacture.

Wire clips, on the other hand, such as those exemplified later in thisinvention can often be made from roll wire in the very applicator whichwill be used to apply these clips. This will take place right on the jobwhere application of the units will be made. Thus application andmanufacture can take place simultaneously. If, in some instances, a morecomplicated clip is deemed advisable for use on some specific job ofapplying the units of wallboard, the clip may be manufactured in thesmallest and most inexpensive type of wire bending machines at properlocations of manufacture. The manufacture anywhere will be at a veryminute fraction of what it costs to make clips from sheet metal.

The use of Celluloid or composition material clips such as Bakelite madesimilar to the wire ones for use in chemical concerns where the metalones will corrode.

From the above descriptions it is evident that these clips do away withface or front nailing on wall board units. Face nailing consists ofnailing the units of wall board through the exposed or front side. Theuse of the clips does away with nail heads showing up on the exposedsurface of the boards, unsightly nail holds on the front surface ofboards, hammer mars and the like. It also does away with shadows whichresult from nailholds, hammer mars and sagging which result from the useof nails. The use of clips also prevents these soft boards from pullingaway completely from the supporting member as is the case with finishingnails and nails with small heads which are generally used in applicationof the units.

The clips in this invention also do away with the use of sheet-metal informing concealed fasteners because they are about twenty times easierto insert, cost only a very small fraction of what the sheet-metal onesdo, and they can be applied at a much faster rate with no inconvenientafter-effects to the workmans fingers, and if an applicator is used theclips may be made and applied in a more speedy simultaneous process.

Certain other specific objects peculiar to each clip will be brought outin connection with these clips as their description and use is, in eachcase, made clear.

All of the fasteners shown in the following figures are concealedrelative to the front surface of a wall unit.

Figure 1 is a side view of one type of concealed fastener.

Figure 2 is a plane view of wall units held together and to underlyingsupports by means of fastener shown in Figure 1.

Figure 3 is a long view along line 50-50 of Figure 2.

Figure 4 is a side view of another type of fastener.

Figure 5 is a view looking down on fastener shown in Figure 4.

Figure 6 is a plane view of units assembled with fastener shown inFigures 4 and 5.

Figure 7 is long view along line 50-50 of Figure 6.

Figure 8 is a perspective of another type of fastener.

Figure 9 is a plane view of units assembled with fasteners as shown inFigure 8.

Figure 10 is a long view taken along line 50-50 of Figure 9.

Figures 11 through 14 are perspectives of clips used similar to thoseshown in Figures 8 through 10.

Figure 15 is perspective of a clip which is a transition between Figure8 and forms shown in Figures 16 through 19.

Figure 16 is a perspective of a clip with end parts pointing indifferent directions, and on a higher horizontal plane than out-jutwhich is adapted to take a nail.

Figure 17 is plane view of units applied with clip shown in Figure 16.

Figure 18 is long view of line 50-50 in Figure 17.

Figure 19 is a perspective of a clip used similar to that shown inFigures 16 through 18.

Figure 20 is a top view of another type of fastener.

Figure 21 is plane view of units applied with clip shown in Figure 20.

Figure 22 is long view along line 50-50 of Figure 21.

Figure 23 is side view of another type of fastener whose applicationdiffers from any of the above.

Figure 24 is plane view of units appliedwith Figures 1 through 3.-InFigure 1, a single wire of a suitable gage is bent so that there is aninsert I, an offset 2, and an out-jut 3. Numerals indicating parts I and3 are arbitrarily called an insert and out-jut in view of their relativeuses in the application of wall board units. In'the case of this clipthey are identical and interchangeable. The wire offset 2, places partsI and 3 angularly projecting in opposite directions with insert on ahigher horizontal plane than out-jut. Units 5 and 6 represent wall boardunits secured to supporting member I by means of clip in unit 5 havingout-jut 3 stapled or nailed to supporting member I, and out-jut 3 ofclip in unit 6 lying between the back surface of the secured and nailedunit 5 and supporting member I. This is accomplished by thrusting insertl of a clip into the edge surface of unit 5 at any given place whereunits 5 and B are to have their abutting edges secured. Clip in unit 5now lies inserted into the unit up to offset 2, with out-jut 3 extendingaway from the edge surface of unit 5 and in the same horizontal plane asthe back of unit five. Out-jut is secured to supporting member by meansof a nail or staple, and then unit 6 has a clip inserted into its edgesurface at any given place, and unit 6 has its edge surface shoved intoabutting relationship with unit 5. As this is done the clip in unit 6has its out-jut 3 pass behind the back surface of the secured unit 5 andthe supporting member I at the abutting edges of units 5 and 6. The sideof unit 6 opposite the abutting units 5 and 6 has clips inserted intoits edge surface and the outjut is secured to the supporting member bymeans of a nail or staple. The next unit to be applied follows the sameprocedure as unit 6 did when its abutting edge was brought into closecontact with unit 5s abutting end surface. Continued application ofunits is a repetition of this method. The clips are spaced in pairs, onefor the abutting surface of one board or unit and one for the abuttingsurface of the other unit. To best secure the boards or units thesepairs should be spaced at 4 to 6 inch intervals along abutting edges ofany two boards or units.

Figures 4 through 7 shows a clip with insert 8, oifset 9, and outjut I0,with terminal loop I2 to accommodate a nail, and anchoring part I I.

The principle involved in the application of this clip on units and tosupporting members is the same as that described under Figures 1 through3. The notable exceptions lie in the construction of the clip ratherthan in its application.

The chief differences lie in the fact that the clip is provided with aloop I2 for holding a nail, and that the terminal end of out-jut I0 iscon tinued to form anchor ll after forming the loop I 2. Anchor IIcatches in the back surfaces of units and prevents any tendency ofoutjut to work free in any unnailed units, or anchor I I may be directeddownward so that it can enter into underlying support of first appliedunit acting in place of a nail or staple in securing unit, in whichfastener has been inserted, to the underlying support. If this'is donethe terminal loop I! may be omitted should this be desirable. Thendistil end of outjut I0 is continued directly, without terminal loop l2,to form anchor H.

Figures 8 through 10.-The clip in Figure 8 is formed by bending astraight piece of wire into a U and then providing a more or lesscentrally placed offset l1 and I1, so that inserts I5 and I5 which arethe inserts of the open part of the U, and the out-juts l8 and [8' willextend angudistil end an open portion ly from the offset angles, orangularly,

' out-jut, may accommodate a nail, this for securing the clip to anyunderlying support.

In application, the same general procedure is followed as that outlinedunderFlguresi through 3. The notable exceptions lie in the constructingof the clip itself, and are as followed below: Each single clip isprovided' with dual inserts l and I5, dual out-Juts l8 and i8 and dualofl'sets l1 and II. The enclosed end of the U in the out-juts are formedby l8 and I8 becoming continuous with each other at distil end ofout-jut.

The out-jutformed by the dual members of wire can accommodate a nail atthe far end of space l9.

Figure 11.-The clip shown here is used the same as those shown above, asalready described. The notable differences in construction are that theout-luts of i8 and I8 lie closer together, and

that the offsets 2'2 and 22' flare out somewhat in theform of a V whichis open below as well as above. This causes inserts l5 and I5 to beplaced far enough from each other so that they will enter the edgesurface of the unit with greater ease than-if there was a tendency forthem to be closer together. The constricted U, in this case, makespossible the utilization of nails with very small heads, this forsecuring the clip to an underlying support where indicated.

Figure 12.The clip shown herein is used similarly to those described inFigures 1 through 3. The notable differences lie in the construction ofthe clip. Out-iuts l8 and I8 are constricted at 23 and 20' so that space2| will be able to accommodate a nail of small size. I

Figure 13.-The clip shown in this drawing has involved the sameprocedure in application as that described and shown under Figures 1through 3. The difierence is in the construction of the clip. Theout-juts l8 and I8 are twisted one half round or more times so that onecomes to overlie the other at 23, providing a loop 24 to accommodate anail for securing it to an underlying support.

here is apphed similar to Figure 14.--Clip the ones already decribed inFigures 1 through 3. The notable differences lie in the construction ofthe clip. The out-jut 28 is formed by a series of twists given tothe-closed end of a U shaped piece of wire, and providing at its most 29which can accommodate a nail or the like. Proximally the twisting iscontinued to include theoffset 25. From the upper part of the offset aretwo extending portions, 25 and 25'. These extend angular- 25, inopposite directions, and lying flush against the edge surface of a boardin which they are used. Extending at right from the extending parts,-the extending parts are continued as inserts 21 and 21. which enter theunit from its edge surface thereof.

Figure 15.The clip shown here is very .much similar to the one showninFigure 8. As shown, the offset 3| is continuous with insert 33. Ifinsert 30 is bent in a direction similar to insert 30', the clip will beexactly like that shown in Figure 8. However, if it is bent in oppositedirections and overlies out-jut I8 or closed portion of U,- applicationis different from other type clips described. To secure abutting edgesof boards with this clip, only one clip is used to secure the abuttingedges of two boards or units at a given place. Insert 30' is thrustintothe end surface of the unit ilrst to be applied, up to offset 3|. Thenout-juts l3 and it are secured by nails to :loists or supporting memberthrough slot l3. Then insert 30 is bent in such a way that it over; liesout-jut l8 which has already been secured to an underlying support by anail or the like. Now, the next unit to be applied is thrust againstpointed end of insert 30 until abutting surfaces of the two units comeinto contact, l8 and I3 coming to lie between the back of the secondapplied unit and the joists or supporting member.

Figures 16 through 18 show clip with out-jut and 35', 35 being slightlylonger than 35'. This sets offsets 34 and 34' to form a plane slightlyoff right angular position in regards to outjut formed by 35 and 35'.Insert 32 extends at approximately a right angle from midline plane50-60. Insert 33 extends at greater than a right angle from plane alongline 50-53. When insert 33 is pressed into the edge surface of the firstapplied unit up to 34, out-jut 35 and 35 extends at an acute angle fromunit 35, and is nailed through 35. The unit 6 which is next applied isthrust on insert 32 until abutting surfaces of 5 and 5am in closecontact.

Figure 19 shows another type clip which is identical to that describedin Figures 15 through 18 in as far as application is concerned. The

- notable difference is in construction of the clip.

It has an oifset 31, an out-jut 38, and nailing portion 39, allcorresponding to offset 25, outjut 28, and nailing portion 29 in Figure14. The inserts 40 and '40 correspond to those shown in Figures 15through 18. 4

Figures 20 through 22 show cl ps with an insert 4|, a centrally placedloop 42, for accommodating a nail, and an insert 43 extending in anopposite direction, but in practically the same horizontal plane asinsert 4|.

To apply: Clip has insert 4| thrust into the distil or abutting surfaceof unit 5 at almost the midthickness of the abutting surface of the unit5 up to loop 42. Then a nail is driven diagonally through loop 42, andpenetrating the unit 5 from its edge surface, it passes through unit 5into underlying joist. Unit 5 has its end or abutting surface thrustagainst insert 43 until edges of units 5 and 6 come into closerelationship. In this manner one clip will hold two boards at any givenplace where it'is used. Therefore it is not necessary to use the clipsin pairs. They should be spaced 4 to 6 inches apart, and used singly.Application at any abutting ends of units as described.

Figures 23 through 25 show clips which secure units from the backsurface thereof about of an inch from the edge of the back surface ofany given place on a unit. Flange 45 is bent from a straight piece ofWire having an extendtrate. through the board to the front surface.

thereby damaging it. The bar prevents flange 45 from pulling out. Whenclip has been driven in back surface of unit 5 at a given place in 4 to6 inch intervals, the unit 5 is stapled or nailed to supports. Then theedge of unit 6 which is to abut secured part of unit I has clips securedin it in the same manner as the edges of unit 5's back surface werehandled. Then unit 8 is shoved together with unit 5 in such a mannerthat the abutting edge of unit 6 will. come into contact with unit 5which has been secured with clips and nailed to an underlying support.The extending portions of unit 6 will pass between the back surface ofsecured unit 5 and the supporting member or joist. Thereby unit 6 issecured at the abutting edges of units 5 and 6. Other abutting edges aresecured in a like manner.

Another use for this clip is shown in Figure 23 and bent into the formof a U, L, or v'is as follows: The preferably shorter prong 45 entersthe substance of the unit at the edge of the unit and passes diagonallyinto the unit, or lies flush against the outer part of a tongue on theunit and has prong 46 penetrate the tongue in a direction towards itsinner surface, or surface nearer the back of the unit, while prong 44penetrates the supporting member or joist, thus securing the unit to theunderlying support. Prong 44 preferably enters the supporting member atthe edge surface of the unit and does not enter the substance of theunit at all.

The preferred application should be such that the tongued edge surfaceof one of these units has the barbed end of a prong entering into it sothat it enters into the substance of the boards tongued edge or liesflush with the surface of the tongue nearer the outer surface of theunit. Prong designated 44, or the one without the barb and which is thelonger of the two, enters the underlying support without entering thesubstance of the panel or unit at all. This secures the edge of the unitto the underlying supporting element. The next unit applied has itsgrooved edge surface pressed onto the tongued portion of the firstapplied unit, and the second unit is held firmly in place at thisabutting relationship. Opposite this the tongued portion of the secondunit is secured by the clips, and the grooved portion of another unit ispressed onto the tongue of the second unit, and by a repetition of thisprocess application may continue.

Figure 26 shows a clip whose application is similar to that shown inFigures 23 through 25. The clip is diflerent in construction, however,in that the terminal end of extending portion 44 is looped at 41 toaccommodate a nail and form a anchor 48.

Figure 27 shows a clip whose application incorporates the same principleas that shown and described in Figures 23 through 25. It diflers inconstruction though. The clip is made from a piece of wire bent in theform of a U having flanges 49 and 49' bent in the same manner and atright angles, or more acutely, to the extending portions of 53 and 53'so that they may slightly overlie 53 and 53'. Flanges 49 and 4! are madeto enter the boards from the back surface, but do not penetrate throughto the front of the board, and are provided with barbs ii and ii forholding flanges 49 and 49' securely in the board. The space 51 takes anail for securing the board to the underlying support.

Figures 28 through 30 show diflerent types of barbs produced by bendingdistil end of inserts or flanges, or by slightly flattening them orcutting them to form a barb at any given place on insert. If it isnecessary to. have a barb on the proper location which will best secureout-jut to back of unit.

Now it can be pointed out that a method for applying all these boardsand units at corner sections, places where wall and ceiling meet, andthe like, is needed as well as a method for application at abuttingedges on a plane surface, as already described.

In the case where ceiling and wall, and the like, meet, the out-juts orextending portions of clips in the ceiling units overlie the upper edgesurface of the units used in the side wall.

A, B, C, and D represent the 4 corners of a room at ceiling level. A isdiagonally across from D, and B is diagonally across from C. Applicationis started along a line of ceiling whose corners are A-B and workedtowards place where side wall meets ceiling on a line between thehypothetical 0-D, and continued until only one section of pieces orunits remain to be applied to complete the ceiling. This one section ofunits lies between the applied units on ceiling surface, and side wallbetween C-D. Application of the first unit of this last section of unitsproceeds to top edges of wall section A-C, just adjacent to corner C,and has extending portions of clips thrust over the top edge surface ofthis wall section, and application is then continued towards corner Duntil last section is put up.

In the case of side wall corners, and the like, in a room, the extendingparts or out-juts of clips in one section of wall units making up wallof one side of a room, at a given corner or the like, are nailed to anunderlying support. The extending portions or out-juts of clips appliedin units, making up the wall adjacent to this at the same corner, arethrust behind the edge surface of the already secured adjacent unitsfrom ceiling to floor at a given comer or the like.

At any given place where adjacent sections of units meet as at cornersof walls from ceiling to floor, or the like, one section of units hasone of its edge surfaces pressed close into the given corner or angularplace, or the like, without clips in edge surface of board firstdirected into the corner. Now, the adjacent side wall units have clipsinserted into edge surfaces, and the out-juts or extending portions arepressed behind the edge surface of the units forming the adjacent wallat this given corner. This secures both sections of units in adJacentwalls at corners or the like.

Three factors are now to be considered:

Wall, board and the like are composition substances which expand andcontract a great deal due to atmospheric changes in temperature andhumidity. The extent of this expansion and contraction necessitates itsserious consideration.

Often removal of units of wall boards take place as a result ofremodeling andthe like.

already been described, is necessary. This is accomplished as follows: Astapling means in an automatic applicator is driven from over outjut ofclip to be secured to underlying support,

this to a depth which will loosely bind out-jut between the staple andsupporting joist. Because of this, extending portion or out-jut may movein the slot formed by the staple in any plane direction in whichexpansion or contraction of the unit may direct it.

In the case of out-juts of sheet-metal clips, these are provided withlongitudinal or transverse slots through which the prongs of the stapleare directed into the underlying support. Or, the stapling means mayhave its prongs directed on each side of the out-jut or the like of asheet metal clip and into the underlying support. This provisionprevents the portion of the clips inserted into the boards fromabsorbing all the brunt of expanding and contracting factors inherent inthe board.

In the case of remodeling:

To take units of wall board down extendin part or out-jut slips frombeneath stapling means when board is pulled in the proper direction.

In the case of providing for the most rapid type of application:

An automatic stapling means driving the staples to the proper depth isused.

The breadth of this patent is to be limited to the broadest possibleinterpretation of the specifications above and the claims to follow.

In the claims the word wire is intended to include not only metalsubstance, but the other materials named herein. The straight portion topierce a wah board edge is adapted topermit these other materials thanwire to withstand the necessary stresses while the offset portion .tounderlie an adjacent wall board clearly will withstand the necessarystresses even though the underlying portion is not of metal.

What I claim is:

1. A blind fastening to secure sections of wall board and the like to asupporting base and to each other without exposure of the fasteningIcomprising a wire staple having a near end and a far end and anintermediate portion angularly disposed placing the ends in differentparallel planes, one of said ends being flat and looped to be fastenedand retained by a nail and the other being straight for insertion intothe edge of a section of wall board.

2. A blind fastening to secure sections of wall board and the like to asupporting base and to each other without exposure of the fasteningmeans, comprising a wire staple having a near end and a far end and anintermediate portion angularly disposed placing the ends in differentparallel planes, and comprising a plurality of prongs adapted to beinserted into the edge of one section of wall board and the other end ina different plane being looped to receive a nail.

each other without exposure of the fastening means. comprising prongsdisposed generally in opposite directions to each other, one beingstraight to penetrate an edge of a wall board, and an intermediateportion generally 01 U -shape connected to the opposed ends by anintermediate offset placing the ends in different parallel planes, theintermediate U portion being in an angular vertical plane with respectto the prongs.

5. A blind fastening to secure sections ofwall board and the like to asupporting base and to each other without exposure of the fastening,comprising a wire staple having a near end that is straight to extendinto an edge of a wall board, and a far end, and an intermediate portionangularly disposed placing the ends in different parallel planes, andbarbs at intermediate positions.

6. A blind fastening to secure sections of wall board and the like to asupporting base and to each other without exposure of the fastening,comprising a wire staple having a near end that .is straight to extendinto an edge of a wall board,

and a far end, and an intermediate portion angularly disposed placingthe ends in different parallel planes, the far end being extended tounderlie an adjacent wall board, and being twisted to form a loop toreceive a nail.

7. A blind fastening to secure sections of wall board and the like to asupporting base and to each other without exposure of the fastening,comprising a wire staple having a near end that is straight to extendinto an edge of a wall board, and a far end, and an intermediate portionangularly disposed placing the ends in different parallel planes, thefar end being adapted ts be forced up into the bottom of an adjacentwall board, the two ends being connected by a lvop extending away fromthe first end and flat to underlie the adjacent wall board.

8. A blind fastening to secure sections of wall board and the like f asupporting base and to each other without exposure of the fastening,comprising a wire staple having a near end that is straight to extendinto an edge of a wall board, and a far end, and an intermediate portionangularly disposed placing the ends in different parallel planes, theintermediate portions being looped and flat to underlie one of the wallboards and being in an angular vertical plane with respectto the ends.

9. A blind fastening to secure sections of wall board and the like to asupporting base and to 3. A blind fastening to secure sections of wallboard and the like to a supporting base and to each other withoutexposure of the fastening means, comprising a wire staple having a nearend and a far end and an intermediate portion angularly disposed placingthe ends in diflerent parallel planes, one of said ends being shaped as8. prong adapted to be inserted into the edge of one section of wallboard and the other end in a different plane having a circular openingto receive a nail, said fastener being bifurcated from the prong end tosaid opening to slidably embrace a pre-driven nail.

4. A blind fastening to secure sections of wall board and the like to asupporting base and to each other without exposure of the fastening.comprising a wire staple having a near end that is straight to extendinto an edge of a wall board, and a far end, and an intermediate portionangularly disposed placing the ends in different parallel planes, theend to penetrate the edge being barbed and the other end being looped toreceive a nail.

10. A blind fastening to secure sections of wall board and the like to asupporting base and to each other without exposure of the fastening,comprising a wire staple having a near end that is straight to extendinto. an edge of a wall board, and a far end, and an intermediateportion angularly disposed placing the ends in different parallelplanes, the end to penetrate the edge being barbed and the other endbeing looped to receive a nail, there being intermediate barbs along thestaple to penetrate adjacent wall boards at different points.

JOHN G. HAMILTON.

